R and S--rewriting rules

The core of address parsing
is the rewriting rules.
These are an ordered list of pattern-replacement rules
which are applied to each address.
The
sendmail
command scans through the set of rewriting rules
looking for a match on the left-hand side
(lhs)
of the rule.
When a rule matches,
the address is replaced by the right-hand side
(rhs)
of the rule.

There are several sets of rewriting rules.
Some of the rewriting sets are used internally
and must have specific semantics.
Other rewriting sets
do not have specifically assigned semantics,
and may be referenced by the mailer definitions
or by other rewriting sets.

The syntax of these two commands is:

Sn

Sets the current ruleset being collected to n.
If you begin a ruleset more than once, it appends it to the old definition.

Rlhsrhscomments

The lhs is a pattern that is applied to the input. If it matches, the input is rewritten to the rhs. The comments are ignored. The fields must be separated by at least one tab character; there may be embedded spaces in the fields.

Macro expansions of the form $x
are performed when the configuration file is read.
A literal $ can be included using $$.
Expansions of the form $&x
are performed at run time using a somewhat less general algorithm.
This is intended only for referencing internally defined macros
such as $h that are changed at runtime.

The left-hand side (LHS)

The left-hand side of rewriting rules contains a pattern.
Normal words are simply matched directly.
Metasyntax is introduced using a dollar sign.
The metasymbols are:

$*

match zero or more tokens

$+

match one or more tokens

$-

match exactly one token

$=x

match any phrase in class x

$~x

match any word not in class x

If any of these match,
they are assigned to the symbol
$n
for replacement on the right-hand side (RHS),
where n is the index in the LHS.
For example, suppose a LHS rule of the following:

$-:$+

Further, suppose the following input:

UCBARPA:eric

In this example, the input matches the rule, and the values
passed to the RHS are:

$1 UCBARPA
$2 eric

Additionally, the LHS can include
$@ to match zero tokens.
This is not bound to a
$n
on the RHS and is normally only used when it stands alone
in order to match the null input.

The right-hand side (RHS)

When the left-hand side of a rewriting rule matches,
the input is deleted and replaced by the right-hand side.
Tokens are copied directly from the RHS,
unless they begin with a dollar sign.
Metasymbols are:

$n

substitutes indefinite token n from LHS

$[name$]

canonicalizes name

$(map key$@arguments$:default$)

generalized keyed mapping function

$>n

calls ruleset n

$#mailer

resolves to mailer

$@host

specifies host

$:user

specifies user

The $n
syntax substitutes the corresponding value from a
$+,
$-,
$*,
$=,
or
$~
match on the LHS.
It can be used anywhere.

A host name enclosed between
$[ and $]
is looked up using the
gethostbyname(SLIB)
routines and replaced by the canonical name.
(This is actually completely equivalent to:

$(hosthostname$)

In particular, a
$:
default can be used.)
For example, $[[128.32.130.2]$] might become
vango.CS.Berkeley.EDU,
and $[csam$] might become lbl-csam.arpa.
sendmail
recognizes its numeric IP address
without calling the name server
and replaces it with its canonical name.

The
$( ... $)
syntax is a more general form of lookup;
it uses a named map instead of an implicit map.
If no lookup is found, the indicated
default is inserted;
if no default is specified and no lookup matches,
the value is left unchanged.
The arguments are passed to the map for possible use.

The $>n syntax
causes the remainder of the line to be substituted as usual
and then passed as the argument to ruleset n.
The final value of ruleset n then becomes
the substitution for this rule.
The $> syntax expands everything after the ruleset name to
the end of the replacement string and then passes that as the
initial input to the ruleset. Recursive calls are allowed.
For example:

$>0 $>3 $1

expands $1, passes that to ruleset 3, and then passes the
result of ruleset 3 to ruleset 0.

The $#
syntax should only be used in ruleset zero or a
subroutine of ruleset zero.
It causes evaluation of the ruleset to terminate immediately,
and it signals to
sendmail
that the address has completely resolved.
The complete syntax is:

$#mailer$@host$:user

This specifies the
{mailer, host, user}
triple necessary to direct the mailer.
If the mailer is local,
the host part can be omitted.
(You may want to use it for special
``per user''
extensions.
For example, at CMU you can send email to
``jgm+foo'';
the part after the plus sign
is not part of the user name,
and is passed to the local mailer for local use.)
The
mailer
must be a single word,
but the
host
and the
user
can be multi-part.
If the
mailer
is the built-in IPC mailer,
the
host
may be a colon-separated list of hosts
that are searched in order for the first working address
(exactly like MX records).
The
user
is later rewritten by the mailer-specific envelope rewriting set
and assigned to the
$u
macro.
As a special case, if mailer specified has the F=@ flag
specified and the first character of the
``$:'' value is ``@'', the ``@''
is stripped off and a flag is set in the address descriptor
that causes sendmail not to do ruleset 5 processing.

Normally, a rule that matches is retried,
that is,
the rule loops until it fails.

A RHS can also be preceded by a
$@
or a
$:
to change this behavior.
A
$@
prefix causes the ruleset to return with the remainder of the RHS
as the value.
A
$:
prefix causes the rule to terminate immediately,
but the ruleset to continue.
This can avoid continued application of a rule.
The prefix is stripped before continuing.

The
$@
and
$:
prefixes can precede a
$>
specification. For example, the form:

R$+ $: $>7 $1

matches anything,
passes that to ruleset seven,
and continues;
the
$:
is necessary to avoid an infinite loop.

Substitution occurs in the order described;
that is,
parameters from the LHS are substituted,
hostnames are canonicalized, ``subroutines'' are called and, finally,
$#,
$@,
and
$:
are processed.

Semantics of rewriting rule sets

There are six rewriting sets that have specific semantics.
Five of these are related as depicted in the figure.

Rewriting set semantics

Ruleset three should turn the address into ``canonical form.''
This form should have the basic syntax:

local-part@host-domain-spec

If no ``@'' sign is specified, then the host-domain-spec
can be appended from the sender address (if the
C
flag is set in the mailer definition corresponding to the sending
mailer).
Ruleset three is applied by
sendmail
before doing anything with any address.

Ruleset zero
is applied after ruleset three
to addresses that are actually going to specify recipients.
It must resolve to a {mailer, host, address}
triple.
The mailer
must be defined in the mailer definitions
from the configuration file.
The host
is defined into the
$h
macro
for use in the argv expansion of the specified mailer.

Rulesets one and two
are applied to all sender and recipient addresses, respectively.
They are applied before any specification
in the mailer definition.
They must never resolve.

Ruleset four is applied to all addresses
in the message.
It is typically used
to translate internal to external form.

In addition, ruleset 5 is applied to all local addresses
(specifically, those that resolve to a mailer with the
F=5 flag set) that do not have aliases. This allows a
last minute hook for local names.

Ruleset hooks

A few extra rulesets are defined as ``hooks''
that can be defined to get special features.
They are all named rulesets. The
``check_*'' forms all give accept/reject status;
falling off the end or returning normally is an accept,
and resolving to $#error is a reject.
Many of these can also resolve to the special mailer name
$#discard;
this accepts the message as though it were successful
but then discards it without delivery.
Note that this mailer can not be chosen as a mailer in ruleset 0.

check_relay

The check_relay
ruleset is called after a connection is accepted by the daemon.
It is not called when sendmail is started using the
-bs option. It is passed

client.host.name $| client.host.address

where
$|
is a metacharacter separating the two parts.
This ruleset can reject connections from various locations.

check_mail

The check_mail
ruleset is passed the user name parameter of the
SMTP MAIL command.
It can accept or reject the address.

check_rcpt

The check_rcpt
ruleset is passed the user name parameter of the
SMTP RCPT command.
It can accept or reject the address.

check_compat

The check_compat ruleset is passed

sender-address $| recipient-address

where $| is a metacharacter separating the addresses.
It can accept or reject mail transfer between these two addresses
much like the checkcompat() function.

check_eoh

The check_eoh ruleset is passed

number-of-headers $| size-of-headers

where $| is a metacharacter separating the numbers.
These numbers can be used for size comparisons with the
arith map. The ruleset is triggered after
all of the headers have been read.
It can be used to correlate information gathered
from those headers using the macro storage map.
One possible use is to check for a missing header. For example:

Keep in mind the Message-Id: header is not a required header and
is not a guaranteed spam indicator.
This ruleset is an example and
should probably not be used in production.

check_etrn

The check_etrn ruleset is passed the parameter of the
SMTP ETRN command. It can accept or reject the command.

check_expn

The check_expn ruleset is passed the user name parameter of the
SMTP EXPN command. It can accept or reject the address.

check_vrfy

The check_vrfy
ruleset is passed the user name parameter of the
SMTP VRFY command.
It can accept or reject the command.

trust_auth

The trust_auth
ruleset is passed the AUTH= parameter of the
SMTP MAIL command.
It is used to determine whether this value should be
trusted. In order to make this decision, the ruleset
may make use of the various ${auth_*} macros.
If the ruleset does resolve to the ``error''
mailer the AUTH= parameter is not trusted and hence
not passed on to the next relay.

tls_client

The tls_client
ruleset is called when sendmail acts as server,
after a STARTTLS command
has been issued, and from check_mail.
The parameter is the value of ${verify}
and STARTTLS or MAIL, respectively.
If the ruleset does resolve to the ``error'' mailer,
the appropriate error code is returned to the client.

tls_server

The tls_server
ruleset is called when
sendmail acts as client after a STARTTLS command
(should) have been issued. The parameter is the value of
${verify}. If the ruleset does resolve to the
``error'' mailer, the connection is aborted
(treated as non-deliverable with a permanent or temporary error).

IPC mailers

Some special processing occurs
if the ruleset zero resolves to an IPC mailer
(that is, a mailer that has ``[IPC]''
listed as the Path in the M configuration line).
The host name passed after ``$@''
has MX expansion performed if not delivering via a named
socket; this looks the name up in DNS to find alternate
delivery sites.

The host name can also be provided as a dotted quad in square brackets;
for example:

[128.32.149.78]

This causes direct conversion of the numeric value
to a TCP/IP host address.

The host name passed in after the
``$@''
may also be a colon-separated list of hosts.
Each is separately MX expanded and the results are concatenated
to make (essentially) one long MX list.
The intent here is to create
``fake''
MX records that are not published in DNS
for private internal networks.

As a final special case, the host name can be passed in
as a text string
in square brackets:

[ucbvax.berkeley.edu]

This form avoids the MX mapping.

NOTE:
This is intended only for situations where you have a network firewall,
so that your MX record points to a gateway machine;
this machine could then do direct delivery to machines
within your local domain.
Use of this feature directly violates RFC 1123 section 5.3.5;
it should not be used lightly.

D--define macro

Macros are named with a single character
or with a word in {braces}.
These can be selected from the entire ASCII set,
but user-defined macros
should be selected from the set of uppercase letters only.
Lowercase letters
and special symbols
are used internally.
Long names beginning with a lower case letter or a punctuation character
are reserved for use by sendmail,
so user-defined long macro names should begin with an upper case letter.

The syntax for macro definitions is:

Dxval

Here
x is the name of the macro and val
is the value it should have.
Macros are interpolated
using the construct
$x,
where
x
is the name of the macro to be interpolated.
This interpolation is done when the configuration file is read,
except in
M
lines.
The special construct
$&x
can be used in
R
lines to get deferred interpolation.

Conditionals can be specified using the syntax:

$?x

if

$|

else

$.

endif

For example:

$?xtext1$|text2$.

This interpolates
text1
if the macro
$x
is set,
and
text2
otherwise.
The ``else'' ($|) clause can be omitted.

Lowercase macro names are reserved to have
special semantics,
used to pass information in or out of
sendmail;
some special characters are reserved to
provide conditionals; and so on.
Uppercase names (that is, $A through $Z)
are specifically reserved for configuration file authors.

The following macros are defined and/or used internally by
sendmail
for interpolation into argv's for mailers
or for other contexts.
The ones marked + are information passed into
sendmail,
the ones marked ++ are information passed both in and out of
sendmail,
and the unmarked macros are passed out of
sendmail
but are not otherwise used internally.

NOTE:
As of sendmail version 8.6,
all of the macros marked + have reasonable defaults.
Previous versions required that they be defined.

$a

the origination date in RFC 822 format.

$b

the current date in RFC 822 format.

$c

the hop count.

$d

the current date in UNIX system (ctime) format.

$e+

(Obsolete; use SmtpGreetingMessage option instead.)
the SMTP entry message.
This is printed out when SMTP starts up.
The first word must be the
$j
macro as specified by RFC 821.
Defaults to
``$j Sendmail $v ready at $b''.
Commonly redefined to include the configuration version number,
for example,
``$j Sendmail $v/$Z ready at $b''.

$f

the sender (from) address.

$g

the sender address relative to the recipient.
For example, if $f is ``foo'' , $g
will be ``host!foo'', ``foo@host.domain'' ,
or whatever is appropriate for the receiving mailer.

$h

the recipient host.
This is set in ruleset 0 from the $@ field of a parsed address.

$i

the queue id. (For example: ``HAA12345'').

$j++

the ``official'' domain name for this site.
This is fully qualified if the full qualification can be found.
It must
be redefined to be the fully qualified domain name
if your system is not configured so that sendmail can find
it automatically.

$k

the UUCP node name (from the uname system call).

$l+

(Obsolete; use UnixFromLine option instead.)
the format of the UNIX mail ``From'' line.
Unless you have changed the UNIX system mailbox format,
you should not change the default, which is
``From $g $d''.

$m

the domain part of the gethostname return value.
Under normal circumstances, $j
is equivalent to ``$w.$m''.

$n+

the name of the daemon (for error messages).
Defaults to ``MAILER-DAEMON''.

$o+

(Obsolete: use OperatorChars option instead.)
the set of ``operators'' in addresses.
This macro defines a list of characters which, during parsing,
are considered tokens and are considered separators of tokens.
For example, if ``@'' were in the
$o
macro, then the input a@b
would be scanned as three tokens: ``a'', ``@'', and ``b''.
Defaults to the characters ``.:@[]'', which is the minimum
set necessary to do RFC 822 parsing;
a richer set of operators is ``.:%@!/[]'', which adds support
for UUCP, the %-hack, and X.400 addresses.

$p

sendmail's process id.

$q+

default format of sender address.
The $q macro specifies how an address should appear
in a message when it is defaulted.
Defaults to ``<$g>''.
It is commonly redefined to be

$?x$x <$g>$|$g$.

or

$g$?x ($x)$.

which correspond to the following two formats:

Eric Allman <eric@CS.Berkeley.EDU>eric@CS.Berkeley.EDU (Eric Allman)

sendmail properly quotes names that have special
characters if the first form is used.

$r

protocol used to receive the message.

$s

sender's host name.

$t

a numeric representation of the current time.

$u

the recipient user.

$v

the version number of sendmail.

$w++

the hostname of this site.
The $w macro is set to the root name of this host
(but see below for caveats).

$x

the full name of the sender.

$z

the home directory of the recipient.

$_

the validated sender address.

${auth_authen}

The client's authentication credentials as determined by authentication
(only set if successful).

${auth_author}

The authorization identity, that is, the AUTH= parameter of the
SMTP MAIL command if supplied.

${auth_type}

The mechanism used for authentication (only set if successful).

${auth_ssf}

The keylength (in bits) of the symmetric encryption algorithm
used for the security layer of a SASL mechanism.

${bodytype}

The message body type (7BIT or 8BITMIME), as determined from the envelope.

${cert_issuer}

The DN (distinguished name) of the CA (certificate authority)
that signed the presented certificate (the cert issuer).

${cert_subject}

The DN of the presented certificate (called the cert subject).

${cipher}

The cipher suite used for the connection, for example: EDH-DSS-DES-CBC3-SHA,
EDH-RSA-DES-CBC-SHA, DES-CBC-MD5, DES-CBC3-SHA.

${cipher_bits}

The keylength (in bits) of the symmetric encryption algorithm
used for a TLS connection.

${client_addr}

The IP address of the SMTP client.
Defined in the SMTP server only.

${client_name}

The host name of the SMTP client.
This may be the client's bracketed IP address
in the form [ nnn.nnn.nnn.nnn ] if the client's
IP address is not resolvable, or if the resolved
name doesn't match ${client_name}.
Defined in the SMTP server only.

${client_port}

The port number of the SMTP client.
Defined in the SMTP server only.

${client_resolve}

Holds the result of the resolve call for
${client_name}: OK, FAIL, FORGED, TEMP.
Defined in the SMTP server only.

${currHeader}

Header value as quoted string
(possibly truncated to MAXNAME).

${daemon_addr}

The IP address the daemon is listening on for connections. Unless
DaemonPortOptions is set, this will be ``0.0.0.0''.

The flags for the daemon as specified by the
Modifier= part of DaemonPortOptions
whereby the flags are separated from each other by spaces,
and upper case flags are doubled. That is,
Modifier=Ea will be represented as
"EE a" in ${daemon_flags} ,
which is required for testing the flags in rulesets.

${daemon_info}

Some information about a daemon as a text string.
For example,
``SMTP+queueing@00:30:00''.

${daemon_name}

The name of the daemon from DaemonPortOptions
Name= suboption. If this suboption is not set,
"Daemon#", where # is the daemon number, is used.

${daemon_port}

The port the daemon is accepting connection on. Unless
DaemonPortOptions is set, this will most likely be
``25''.

${deliveryMode}

The current delivery mode sendmail is using.
It is initially set to the value of the
DeliveryMode option.

${envid}

The envelope id passed to sendmail as part of the envelope.

${hdrlen}

The length of the header value which is stored in
${currHeader} (before possible truncation).
If this value is greater than or equal MAXNAME
the header has been truncated.

${hdr_name}

The name of the header field for which the current header
check ruleset has been called.
This is useful for a default header check ruleset to get
the name of the header.

${if_addr}

The IP address of the interface of an incoming connection
unless it is in the loopback net.

${if_name}

The name of the interface of an incoming connection.
This macro can be used for
SmtpGreetingMessage and HReceived for virtual hosting.
For example:

O SmtpGreetingMessage=$?{if_name}${if_name}$|$j$. Sendmail $v/$Z; $b

${mail_addr}

The address part of the resolved triple of the address given for the
SMTP MAIL command. Defined in the SMTP server only.

${mail_host}

The host from the resolved triple of the address given for the
SMTP MAIL command. Defined in the SMTP server only.

${mail_mailer}

The mailer from the resolved triple of the address given for the
SMTP MAIL command. Defined in the SMTP server only.

${ntries}

The number of delivery attempts.

${opMode}

The current operation mode (from the -b flag).

${queue_interval}

The queue run interval given by the -q flag. For example,
-q30m would set ${queue_interval} ``00:30:00''.

${rcpt_addr}

The address part of the resolved triple of the address given for the
SMTP RCPT command. Defined in the SMTP server only.

${rcpt_host}

The host from the resolved triple of the address given for the
SMTP RCPT command. Defined in the SMTP server only.

${rcpt_mailer}

The mailer from the resolved triple of the address given for the
"SMTP RCPT command. Defined in the SMTP server only.

${server_addr}

The address of the server of the current outgoing SMTP connection.

${server_name}

The name of the server of the current outgoing SMTP connection.

${tls_version}

The TLS/SSL version used for the connection, (example: TLSv1, SSLv3, SSLv2.)

${verify}

The result of the verification of the presented cert. Possible values are:

OK

verification succeeded.

NO

no cert presented.

FAIL

cert presented but could not be verified, for example,
the signing CA is missing.

NONE

STARTTLS has not been performed.

TEMP

temporary error occurred.

PROTOCOL

some protocol error occurred.

SOFTWARE

STARTTLS handshake failed.

There are three types of dates that can be used.
The $a and $b macros are in RFC 822 format;
$a is the time as extracted from the ``Date:''
line of the message (if there was one), and $b
is the current date and time (used for postmarks).
If no ``Date:'' line is found in the incoming message,
$a is set to the current time also. The $d
macro is equivalent to the $b macro in UNIX system
(ctime) format. The macros $w, $j, and
$m are set to the identity of this host.
sendmail tries to find the fully qualified name of the host
if at all possible; it does this by calling
gethostname(SLIB)
to get the current hostname
and then passing that to
gethostbyname(SLIB)
which is supposed to return the canonical version of that host name.
(For example, on some systems
gethostname
might return
``foo''
which would be mapped to
foo.bar.com
by gethostbyname.)
Assuming this is successful,
$j
is set to the fully qualified name
and
$m
is set to the domain part of the name
(everything after the first dot).
The
$w
macro is set to the first word
(everything before the first dot)
if you have a level 5 or higher configuration file;
otherwise, it is set to the same value as
$j.
If the canonification is not successful,
it is imperative that the configuration file set
$j
to the fully qualified domain name.
(Earlier versions of sendmail did not pre-define
$j
at all, so up until sendmail version 8.6,
configuration files
always
had to define
$j.)

The
$f
macro is the ID of the sender
as originally determined;
when you are mailing to a specific host,
the
$g
macro is set to the address of the sender
relative to the recipient.
For example, if eric sends to
bollard@matisse.CS.Berkeley.EDU
from the machine vango.CS.Berkeley.EDU, the
$f
macro is ``eric'' and the
$g
macro is ``eric@vango.CS.Berkeley.EDU''.

The
$x
macro is set to the full name of the sender.
This can be determined in several ways.
It can be passed as a flag to
sendmail.
The second choice is the value of the ``Full-name:''
line in the header if it exists,
and the third choice is the comment field
of a ``From:'' line.
If all of these fail, and if the message is being originated locally,
the full name
is looked up in the
/etc/passwd
file.

When sending,
the
$h,
$u,
and
$z
macros are set to the host, user, and home directories
(if local)
of the recipient.
The first two are set from the
$@
and
$:
parts of the rewriting rules, respectively.

The
$p
and
$t
macros create unique strings
(for example, for the ``Message-Id:'' field).
The
$i
macro is set to the queue ID on this host;
if put into the timestamp line,
it can be extremely useful for tracking messages.
The
$v
macro is set to be the version number of
sendmail;
this is normally put in timestamps
and has proved extremely useful for debugging.

The
$c
macro is set to the
``hop count,''
that is, the number of times this message has been processed.
This can be determined
by the
-h
flag on the command line
or by counting the timestamps in the message.

The $r and $s
macros are set to the protocol used to communicate with
sendmail and the sending hostname.

The $_ macro is set to a validated sender host name.
If the sender is running an RFC 1413 compliant IDENT server
and the receiver has the IDENT protocol turned on,
it will include the user name on that host.

The ${client_name}, ${client_addr},
and ${client_port} macros
are set to the name, address, and port number of the SMTP client
who is invoking sendmail as a server.
These can be used in the check_* rulesets (using the
$& deferred evaluation form).

C and F--define classes

Classes of phrases may be defined
to match on the left-hand side of rewriting rules,
where a ``phrase'' is a sequence of characters that do not contain
space characters.
For example, a class of all local names for this site
might be created so that attempts to send to oneself
can be eliminated.
These can either be defined directly in the configuration file
or read in from another file.
Classes are named as a single letter or a word in {braces}.
Class names beginning with lower case letters
and special characters are reserved for system use.
Classes defined in config files may be given names
from the set of upper case letters for short names
or beginning with an upper case letter for long names.

The syntax is:

Ccphrase1 phrase2...Fcfile

The first form defines the class
c
to match any of the named words.
It is permissible to split them among multiple lines,
for example:

CHmonet ucbmonet

This example is equivalent to the following:

CHmonet
CHucbmonet

The ``F'' form reads the elements of the class
c from the named file.
Each element should be listed on a separate line.
To specify an optional file, use ``-o'' between the class
name and the file name, for example:

Fc -o /path/to/file

If the file cannot be used,
sendmail will not complain but silently ignore it.

Elements of classes can be accessed in rules using
$= or $~.
The $~ (match entries not in class)
only matches a single word;
multi-word entries in the class are ignored in this context.

Some classes have internal meaning to sendmail:

$=e

contains the Content-Transfer-Encodings that can be 87 bit encoded.
It is predefined to contain
``7bit'', ``8bit'', and ``binary''.

$=k

set to be the same as
$k, that is, the UUCP node name.

$=m

set to the set of domains by which this host is known,
initially just $m.

$=n

can be set to the set of MIME body types
that can never be eight to seven bit encoded.
It defaults to ``multipart/signed''.
Message types ``message/*'' and ``multipart/*''
are never encoded directly.
Multipart messages are always handled recursively.
The handling of message/* messages
are controlled by class $=s.

$=q

A set of Content-Types that will never be encoded as base64
(if they have to be encoded, they will be encoded as quoted-printable).
It can have primary types (for example: ``text'') or full types
(such as ``text/plain''). The class is initialized to have ``text/plain''
only.

$=s

contains the set of subtypes of message that can be treated recursively.
By default it contains only
``rfc822''. Other ``message/*''
types cannot be 87 bit encoded.
If a message containing eight bit data is sent to a seven bit host,
and that message cannot be encoded into seven bits,
it will be stripped to 7 bits.

$=t

set to the set of trusted users by the
T configuration line.
If you want to read trusted users from a file, use
Ft/file/name.

$=w

set to be the set of all names this host is known by.
This can be used to match local hostnames.

$={persistentMacros}

set to the macros would should be saved across queue runs.
Care should be taken when adding macro names to this class.

sendmail can be compiled to allow a
scanf(S)
string on the F line.
This lets you do simplistic parsing of text files.
For example, to read all the user names in your system
/etc/passwd file into a class, use

FL/etc/passwd %[^:]

which reads every line up to the first colon.

M--define mailer

Programs and interfaces to mailers
are defined in this line.
The format is:

Mname, {field=value}*

Here
name
is the name of the mailer (used internally only)
and the ``field=name'' pairs define attributes of the mailer.
Fields are:

Path

The pathname of the mailer

Flags

Special flags for this mailer

Sender

Rewriting set(s) for sender addresses

Recipient

Rewriting set(s) for recipient addresses

Argv

An argument vector to pass to this mailer

Eol

The end-of-line string for this mailer

Maxsize

The maximum message length to this mailer

maxmessages

The maximum message deliveries per connection

Linelimit

The maximum line length in the message body

Directory

The working directory for the mailer

Userid

The default user and group id to run as

Nice

The nice increment for the mailer

Charset

The default character set for 8-bit characters

Type

Type information for DSN diagnostics

Wait

The maximum time to wait for the mailer

/

The root directory for the mailer

Only the first character of the field name is checked.

The following flags may be set in the mailer description.
Any other flags may be used freely to
conditionally assign headers to messages
destined for particular mailers.

A

Look up the user part of the address in the alias database.
Normally this is only set for local mailers.

force a blank line on the end of a message.
This is intended to work around some versions of
/bin/mail
that require a blank line, but do not provide it themselves.
It would not normally be used on network mail.

c

do not include comments in addresses.
This should only be used if you have to work around
a remote mailer that gets confused by comments.

C

If mail is received from a mailer with this flag set,
any addresses in the header that do not have an at sign
(``@'')
after being rewritten by ruleset three
have the
@domain
clause from the sender
tacked on.
This allows mail with headers of the following form to be rewritten
automatically; for example:

From: usera@hosta
To: userb@hostb, userc

becomes:

From: usera@hosta
To: userb@hostb, userc@hosta

d

Do not include angle brackets around route-address syntax addresses.
This is useful on mailers that are going to pass addresses to a shell
that might interpret angle brackets as I/O redirection.
However, it does not protect against other shell metacharacters.
Therefore, passing addresses to a shell should not be considered secure.

D

This mailer wants a
``Date:''
header line.

e

This mailer is expensive to connect to,
so try to avoid connecting normally.
Any necessary connection occurs during a queue run.

E

escape lines beginning with
``From''
in the message with a ``>'' sign.

f

The mailer wants a
-ffrom
flag,
but only if this is a network forward operation
(that is,
the mailer gives an error
if the executing user
does not have special permissions).

F

This mailer wants a
``From:''
header line.

g

Normally,
sendmail
sends internally generated email
(for example, error messages)
using the null return address
as required by RFC 1123.
(Actually, this only applies to SMTP,
which uses the ``MAIL FROM:<>'' command.)
However, some mailers do not accept a null return address.
If necessary,
you can set the
g
flag to prevent
sendmail
from obeying the standards;
error messages will be sent as from the MAILER-DAEMON
(actually, the value of the
$n
macro).

h

Uppercase should be preserved in host names
for this mailer.

i

Do User Database rewriting on envelope sender address.

I

This mailer is speaking SMTP
to another sendmail.
As such, it can use special protocol features.
This option is not required
(that is,
if this option is omitted, the transmission still operates successfully,
although perhaps not as efficiently as possible).

j

Do User Database rewriting on recipients as well as senders.

k

Normally when sendmail
connects to a host via SMTP,
it checks to make sure that this isn't accidentally the same host name
as might happen if sendmail
is misconfigured or if a long-haul network interface is set in loopback mode.
This flag disables the loopback check.
It should only be used under very unusual circumstances.

l

This mailer is local
(that is,
final delivery is performed).

L

Limit the line lengths as specified in RFC 821.
This deprecated option should be replaced by the
``L=''
mail declaration.
For historic reasons, the
L
flag also sets the
7
flag.

m

This mailer can send to multiple users
on the same host
in one transaction.
When a
$u
macro occurs in the
argv
part of the mailer definition,
that field is repeated as necessary
for all qualifying users.
Removing this flag can defeat duplicate suppression on a remote site
as each recipient is sent in a separate transaction.

M

This mailer wants a
``Message-Id:''
header line.

n

Do not insert a UNIX system style
``From:'' line on the front of the message.

o

Always run as the owner of the recipient mailbox.
Normally sendmail runs as the sender for locally generated mail
or as ``daemon'' (actually, the user specified in the
u option) when delivering network mail.
The normal behavior is required by most local mailers,
which will not allow the envelope sender address
to be set unless the mailer is running as daemon.
This flag is ignored if the S flag is set.

p

Use the route-addr style reverse-path in the SMTP
``MAIL FROM:''
command,
rather than just the return address.
Although this is required in RFC 821 section 3.1,
many hosts do not process reverse-paths properly.
Reverse-paths are officially discouraged by RFC 1123.

P

This mailer requires a
``Return-Path:''
line.

q

When an address that resolves to this mailer is
verified (SMTP VRFY command), generate 250 responses
instead of 252 responses. This will imply that the
address is local.

r

This is the same as
f,
but sends a
-r
flag.

R

Open SMTP connections from a "secure" port. Secure
ports aren't (secure, that is) except on UNIX machines,
so it is unclear that this adds anything.

s

Strip quote characters off the address
before calling the mailer.

S

Do not reset the user ID
before calling the mailer.
This would be used in a secure environment
where
sendmail
ran as root.
This could be used to avoid forged addresses.
If the U= field is also specified, this flag causes the
effective user id to be set to that user.

u

Uppercase should be preserved in user names
for this mailer.
Standards require preservation of case in the local part
of addresses, except for those addresses for which your
system accepts responsibility.

U

This mailer wants UNIX system style ``From''
lines with the UUCP-style
``remote from <host>''
on the end.

w

The user must have a valid account on this machine,
that is,
getpwnam must succeed. If not, the mail is bounced.
This is required to get ``.forward'' capability.

x

This mailer wants a
``Full-Name:''
header line.

X

This mailer wants to use the hidden dot algorithm
as specified in RFC 821.
Basically,
any line beginning with a dot
has an extra dot prepended
(to be stripped at the other end).
This ensures that lines in the message containing a dot
do not terminate the message prematurely.

z

Run Local Mail Transfer Protocol (LMTP) between
sendmail and the local mailer.
This is a variant on SMTP defined in RFC 2033
that is specifically designed for delivery to a local mailbox.

0

Don't look up MX records for hosts sent via SMTP.

3

Extend the list of characters converted to =XX notation
when converting to Quoted-Printable
to include those that don't map cleanly between ASCII and EBCDIC.
Useful if you have IBM mainframes on site.

5

If no aliases are found for this address,
pass the address through ruleset 5 for possible alternate resolution.
This is intended to forward the mail to an alternate delivery spot.

6

Strip headers to seven bits.

7

Strip all output to seven bits.
This is the default if the
L flag is set.
Note that clearing this option is not
sufficient to get full eight bit data passed through
sendmail. If the 7
option is set, this is essentially always set,
since the eighth bit was stripped on input.
Note that this option will only impact messages
that didn't have 87 bit MIME conversions performed.

8

If set, it is acceptable to send eight bit data to this mailer;
the usual attempt to do 87 bit MIME conversions will be bypassed.

9

If set, do limited
78 bit MIME conversions.
These conversions are limited to text/plain data.

:

Check addresses to see if they begin
``:include:''; if they do, convert them to the
``*include*'' mailer.

|

Check addresses to see if they begin with a `|';
if they do, convert them to the ``prog''
mailer.

/

Check addresses to see if they begin with a `/';
if they do, convert them to the ``*file*'' mailer.

@

Look up addresses in the user database.

%

Do not attempt delivery on initial recipient of a message
or on queue runs
unless the queued message is selected
using one of the -qI/-qR/-qS queue run modifiers
or an ETRN request.

The mailer with the special name
``error''
can be used to generate a user error.
The (optional) host field is an exit status to be returned,
and the user field is a message to be printed.
The exit status may be numeric or one of the values
USAGE, NOUSER, NOHOST, UNAVAILABLE,
SOFTWARE, TEMPFAIL, PROTOCOL, or CONFIG
to return the corresponding EX_ exit code, or an
enhanced error code as described in RFC 1893
(Enhanced Mail System Status Codes).
For example, the entry:

$#error $@ NOHOST $: Host unknown in this domain

on the RHS of a rule
will cause the specified error to be generated
and the
``Host unknown''
exit status to be returned
if the LHS matches.
This mailer is only functional in rulesets 0, 5,
or one of the check_* rulesets.

The mailer with the special name discard causes any mail
sent to it to be discarded but otherwise treated as though it
were successfully delivered. This mailer can not be used in
ruleset 0, only in the various address checking rulesets.

The mailer named
``local''
must
be defined in every configuration file.
This is used to deliver local mail,
and is treated specially in several ways.
Additionally, three other mailers named
``prog'',
``*file*'',
and
``*include*''
may be defined to tune the delivery of messages to programs,
files, and :include: lists respectively.
They default to:

The Sender and Recipient rewriting sets
may either be a simple ruleset id
or may be two ids separated by a slash;
if so, the first rewriting set is applied to envelope
addresses
and the second is applied to headers.

The Directory
is actually a colon-separated path of directories to try.
For example, the definition
``D=$z:/''
first tries to execute in the recipient's home directory;
if that is not available,
it tries to execute in the root of the filesystem.
This is intended to be used only on the
``prog''
mailer,
because some shells (such as
csh)
refuse to execute if they cannot read the home directory.
Because the queue directory is not normally readable by normal users
csh
scripts as recipients can fail.

The Userid specifies the default user and group id to run as,
overriding the DefaultUser option (q.v.).
If the S mailer flag is also specified,
this user and group will be set as the effective uid and gid for the process.
This may be given as user:group to set both the user and group id;
either may be an integer or a symbolic name to be looked up
in the passwd and group
files respectively. If only a symbolic user name is specified,
the group id in the passwd
file for that user is used as the group id.

The Charset field
is used when converting a message to MIME;
this is the character set used in the
Content-Type: header. If this is not set, the
DefaultCharset option is used,
and if that is not set, the value ``unknown-8bit'' is used.

WARNING:
This field applies to the sender's mailer,
not the recipient's mailer.
For example, if the envelope sender address
lists an address on the local network
and the recipient is on an external network,
the character set will be set from the Charset= field
for the local network mailer,
not that of the external network mailer.

The Type= field sets the type information
used in MIME error messages as defined by RFC 1894.
It is actually three values separated by slashes:
the MTA-type (that is, the description of how hosts are named),
the address type (the description of e-mail addresses),
and the diagnostic type (the description of error diagnostic codes).
Each of these must be a registered value
or begin with ``X-.'' The default is ``dns/rfc822/smtp''.

The m= field specifies the maximum number of messages to attempt to deliver
on a single SMTP or LMTP connection.

The /= field specifies a new root directory for the mailer. The path is
macro expanded and then passed to the ``chroot''
system call. The root directory is changed before the Directory field is
consulted or the uid is changed.

The Wait= field specifies the maximum time to wait for the
mailer to return after sending all data to it.
This applies to mailers that have been forked by
sendmail.

H--define header

The format of the header lines that sendmail
inserts into the message are defined by the
H line.
The syntax of this line is one of the following:

Continuation lines in this spec
are reflected directly into the outgoing message.
The htemplate
is macro-expanded before insertion into the message. If the
mflags (surrounded by question marks)
are specified, at least one of the specified flags
must be stated in the mailer definition
for this header to be automatically output.
If a ${macro} (surrounded by question marks)
is specified, the header will be automatically output
if the macro is set. The macro may be set using any of the normal methods,
including using the macro storage map in a ruleset.
If one of these headers is in the input it is reflected to the output
regardless of these flags or macros.

Some headers have special semantics that will be described later.

A secondary syntax allows validation of headers as they are being read.
To enable validation, use:

HHeader:$>RulesetHHeader:$>+Ruleset

The indicated Ruleset
is called for the specified Header,
and can return $#error
to reject the message or $#discard
to discard the message (as with the other check_ *
rulesets). The header is treated as a structured field,
that is, comments (in parentheses) are deleted before processing,
unless the second form
$>+
is used.

A default ruleset that is called for headers which don't have a
specific ruleset defined for them can be specified by:

H*:$>Ruleset

or

H*:$>+Ruleset

O--set option

There are a number of global options that
can be set from a configuration file.
Options are represented by full words;
some are also representable as single characters
for backwards compatibility. The syntax of this line is:

O option=value

This sets option option
to be value. Note that there
must
be a space between the letter `O' and the name of the option.
An older version is:

Oovalue

where the option o
is a single character. Depending on the option,
value may be a string, an integer,
a boolean (with legal values
``t,'' ``T,'' ``f,'' or ``F'';
the default is TRUE), or a time interval.

The options supported (with the old, one character names in brackets) are:

AliasFile=spec, spec, ...

[A] Specify possible alias file(s). Each
spec should be in the format
``class:file''
where class:
is optional and defaults to ``implicit''.
Depending on how sendmail
is compiled, valid classes are ``implicit''
(search through a compiled-in list of alias file types,
for back compatibility), ``hash'' (if NEWDB
is specified), ``dbm'' (if NDBM is specified),
``stab'' (internal symbol table - not normally used
unless you have no other database lookup), or ``nis''
(if NIS is specified). If a list of
spec s are provided, sendmail
searches them in order.

AliasWait=timeout

[a] If set, wait up to timeout
(units default to minutes) for an ``@:@''
entry to exist in the alias database
before starting up. If it does not appear in the
timeout interval
rebuild the database (if the AutoRebuildAliases
option is also set) or issue a warning.

AllowBogusHELO

[no short name]
If set, allow HELO SMTP commands that don't include a host name.
Setting this violates RFC 1123 section 5.2.5,
but is necessary to interoperate with several SMTP clients.
If there is a value, it is still checked for legitimacy.

AuthMechanisms

[no short name]
List of authentication mechanisms for AUTH (separated by spaces).
The advertised list of authentication mechanisms will be the
intersection of this list and the list of available mechanisms as
determined by the Cyrus SASL library.

AuthOptions

[no short name]
When to use the AUTH= parameter for the MAIL FROM command;

A Only when authentication succeeded.

The default is to try whenever SMTP AUTH is available.

AutoRebuildAliases

[D] If set,
rebuild the alias database if necessary and possible.
The rebuild will happen the next time an alias is looked up.
If this option is not set,
sendmail
will never rebuild the alias database
unless explicitly requested using
-bi.

NOTE:
There is a potential for a denial of service attack if this is set.
This option is deprecated and
will be removed from a future version.

BlankSub=c

[B] Set the blank substitution character to
c.
Unquoted spaces in addresses are replaced by this character.
Defaults to space (that is, no change is made).

CACERTPath

[no short name]
Path to directory with certificates of CAs.

CACERTFile

[no short name]
File containing one CA certificate.

CheckAliases

[n]
Validate the RHS of aliases when rebuilding the alias database.

CheckpointInterval=N

[C]
Checkpoints the queue every
N
(default 10)
addresses sent.
If your system crashes during delivery to a large list,
this prevents retransmission to any but the last
N recipients.

ClassFactor=fact

[z]
The indicated
factor
is multiplied by the message class
(determined by the Precedence: field in the user header
and the
P
lines in the configuration file)
and subtracted from the priority.
Thus, messages with a higher Priority: will be favored.
Defaults to 1800.

ClientCertFile

[no short name]
File containing the certificate of the client, that is, this certificate
is used when sendmail acts as client.

ClientPortOptions=options

[O]
Set client SMTP options.
The options are
key=value
pairs separated by commas.
Known keys are:

Port

Name/number of source port for connection (defaults to any free port)

Addr

Address mask (defaults INADDR_ANY)

Family

Address family (defaults to INET)

SndBufSize

Size of TCP send buffer

RcvBufSize

Size of TCP receive buffer

Modifier

Options (flags) for the daemon

The
Address
mask may be a numeric address in dot notation
or a network name.
Modifier
can be the following character:

h use name of interface for HELO command

If ``h'' is set, the name corresponding to the outgoing interface
address (whether chosen via the Connection parameter or
the default) is used for the HELO/EHLO command.

ClientKeyFile

[no short name]
File containing the private key belonging to the client certificate.

ColonOkInAddr

[no short name]
If set, colons are acceptable in e-mail addresses
(for example,
``host:user ).''
If not set, colons indicate the beginning of a RFC 822 group construct
``"groupname: member1, member2, ... memberN;" ).''
Doubled colons are always acceptable
``nodename::user )''
and proper route-addr nesting is understood
``<@relay:user@host> ).''
Furthermore, this option defaults on if the configuration version level
is less than 6 (for back compatibility).
However, it must be off for full compatibility with RFC 822.

ConnectionCacheSize=N

[k]
The maximum number of open connections that will be cached at a time.
The default is one.
This delays closing the current connection until
either this invocation of
sendmail
needs to connect to another host
or it terminates.
Setting it to zero defaults to the old behavior,
that is, connections are closed immediately.
Since this consumes file descriptors,
the connection cache should be kept small:
4 is probably a practical maximum.

ConnectionCacheTimeout=timeout

[K]
The maximum amount of time a cached connection will be permitted to idle
without activity.
If this time is exceeded,
the connection is immediately closed.
This value should be small (on the order of ten minutes).
Before
sendmail
uses a cached connection,
it always sends a RSET command
to check the connection;
if this fails, it reopens the connection.
This keeps your end from failing if the other end times out.
The point of this option is to be a good network neighbor
and avoid using up excessive resources
on the other end.
The default is five minutes.

ConnectOnlyTo=address

[no short name]
This can be used to
override the connection address (for testing purposes).

ConnectionRateThrottle=N

[no short name]
If set to a positive value,
allow no more than
N
incoming daemon connections in a one second period.
This is intended to flatten out peaks
and allow the load average checking to cut in.
Defaults to zero (no limits).

ControlSocketName=name

[no short name]
Name of the control socket for daemon management.
A running
sendmail
daemon can be controlled through this named socket.
Available commands are:
help,restart,shutdown,
and
status.
The
status
command returns the current number of daemon children,
the maximum number of daemon children,
the free disk space (in blocks) of the queue directory,
and the load average of the machine expressed as an integer.
If not set, no control socket will be available.

DHParameters

File with DH parameters for STARTTLS.
This is only required if DSA/DH is used.

DaemonPortOptions=options

[O]
Set server SMTP options.
Each instance of DaemonPortOptions leads to an additional incoming socket.
The options are
key=value pairs. Known keys are:

Name

User-definable name for the daemon (defaults to "Daemon#")

Port

Name/number of listening port (defaults to "smtp")

Addr

Address mask (defaults INADDR_ANY)

Family

Address family (defaults to INET)

Listen

Size of listen queue (defaults to 10)

Modifier

Options (flags) for the daemon

SndBufSize

Size of TCP send buffer

RcvBufSize

Size of TCP receive buffer

The Name
field is used for error messages and logging.
The Addr ess
mask may be a numeric address in dot notation
or a network name. The Family
key defaults to INET (IPv4).
Modifier can be a sequence (without any delimiters)
of the following characters:

a

always require authentication

b

bind to interface through which mail has been received

c

perform hostname canonification (.cf)

f

require fully qualified hostname (.cf)

u

allow unqualified addresses (.cf)

C

don't perform hostname canonification

E

disallow ETRN (see RFC 2476)

That is, one way to specify a message submission agent (MSA) that
always requires authentication is:

O DaemonPortOptions=Name=MSA, Port=587, M=Ea

The modifiers that are marked with "(.cf)" have only
effect in the standard configuration file, in which
they are available via ${daemon_flags}.
The flags ``c'' and ``C'' can change the default for
hostname canonification in the sendmail.cf file.
The modifier ``f'' disallows addresses of the form user@host
unless they are submitted directly.
The flag ``u'' allows unqualified sender addresses.
``b'' forces sendmail to bind to the interface
through which the e-mail has been
received for the outgoing connection.

WARNING:
Use ``b''
only if outgoing mail can be routed through the incoming connection's
interface to its destination. No attempt is made to catch problems due to a
misconfiguration of this parameter, use it only for virtual hosting
where each virtual interface can connect to every possible location.
This will also override possible settings via
ClientPortOptions.sendmail
will listen on a new socket
for each occurrence of the DaemonPortOptions option
in a configuration file.

DefaultAuthInfo

[no short name]
Filename that contains default authentication information for outgoing
connections. This file must contain the user id, the authorization id,
the password (plain text), and the realm to use
on separate lines and must be readable by
root (or the trusted user) only.
If no realm is specified,
$j is used.

DefaultCharSet=charset

[no short name]
When a message that has 8-bit characters but is not in MIME format
is converted to MIME
(see the EightBitMode option)
a character set must be included in the Content-Type: header.
This character set is normally set from the Charset= field
of the mailer descriptor.
If that is not set, the value of this option is used.
If this option is not set, the value
``unknown-8bit'' is used.

DataFileBufferSize=threshold

[no short name]
Set the threshold,, in bytes,
before a memory-based queue data file
becomes disk-based. The default is 4096 bytes.

DeadLetterDrop=file

[no short name]
Defines the location of the system-wide dead.letter file,
formerly hardcoded to /usr/tmp/dead.letter.
If this option is not set (the default), sendmail
will not attempt to save to a system-wide dead.letter
file in the event
it cannot bounce the mail to the user or postmaster.
Instead, it will rename the qf file
as it has in the past
when the dead.letter file could not be opened.

DefaultUser=user:group

[u] Set the default userid for mailers to
user:group..
If group is omitted and user
is a user name (as opposed to a numeric user id)
the default group listed in the /etc/passwd file for that user is used
as the default group. Both user and group
can be numeric. Mailers without the S
flag in the mailer definition will run as this user. Defaults to 1:1.
The value can also be given as a symbolic user name.
(The old g option has been combined into the
DefaultUser option).

DeliveryMode=x

[d] Deliver in mode
x.. Legal modes are:

i

Deliver interactively (synchronously)

b

Deliver in background (asynchronously)

q

Just queue the message (deliver during queue run)

d

Defer delivery and all map lookups (deliver during queue run)

Defaults to ``b'' if no option is specified,
``i'' if it is specified but given no argument
(that is, ``Od'' is equivalent to ``Odi'').
The -v command line flag sets this to
i..

DialDelay=sleeptime

[no short name]
Dial-on-demand network connections can see timeouts
if a connection is opened before the call is set up.
If this is set to an interval and a connection times out
on the first connection being attempted
sendmail
will sleep for this amount of time and try again.
This should give your system time to establish the connection
to your service provider.
Units default to seconds, so
``DialDelay=5''
uses a five second delay.
Defaults to zero
(no retry).

DontBlameSendmail=option,option,...

[no short name]
In order to avoid possible cracking attempts
caused by world- and group-writable files and directories,
sendmail
does paranoid checking when opening most of its support files.
If for some reason you absolutely must run with,
for example, a group-writable /etc directory,
then you will have to turn off this checking
(at the cost of making your system more vulnerable to attack).
The arguments are individual options that turn off checking:

Safe is the default.
The details of these flags are described above.
Use of this option is not recommended.

DontExpandCnames

[no short name]
The standards say that all host addresses used in a mail message
must be fully canonical.
For example, if your host is named ``Cruft.Foo.ORG''
and also has an alias of ``FTP.Foo.ORG'',
the former name must be used at all times.
This is enforced during host name canonification
($[ ... $] lookups).
If this option is set, the protocols are ignored and the
``wrong'' thing is done.
However, the IETF is moving toward changing this standard,
so the behavior may become acceptable.
Please note that hosts downstream may still rewrite the address
to be the true canonical name however.

DontInitGroups

[no short name]
If set, sendmail
will avoid using the initgroups call.
If you are running NIS,
this causes a sequential scan of the groups.byname map,
which can cause your NIS server to be badly overloaded in a large domain.
The cost of this is that the only group found for users
will be their primary group (the one in the password file),
which will make file access permissions somewhat more restrictive.
Has no effect on systems that don't have group lists.

DontProbeInterfaces

[no short name]
sendmail
normally finds the names of all interfaces active on your machine
when it starts up
and adds their name to the
$=w
class of known host aliases.
If you have a large number of virtual interfaces
or if your DNS inverse lookups are slow
this can be time consuming.
This option turns off that probing.
However, you will need to be certain to include all variant names
in the
$=w
class by some other mechanism.

DontPruneRoutes

[R]
Normally,
sendmail
tries to eliminate any unnecessary explicit routes
when sending an error message
(as discussed in RFC 1123 § 5.2.6).
For example,
when sending an error message to

<@known1,@known2,@known3:user@unknown>

sendmail
will strip off the
``@known1,@known2''
in order to make the route as direct as possible.
However, if the
R
option is set, this will be disabled,
and the mail will be sent to the first address in the route,
even if later addresses are known.
This may be useful if you are caught behind a firewall.

DoubleBounceAddress=error-address

[no short name]
If an error occurs when sending an error message,
send the error report (termed a ``double bounce''
because it is an error bounce
that occurs when trying to send another error
bounce ) to the indicated address.
The address is macro expanded
at the time of delivery.
If not set, defaults to
``postmaster''.

EightBitMode=action

[8]
Set handling of eight-bit data.
There are two kinds of eight-bit data:
that declared as such using the
BODY=8BITMIME
ESMTP declaration or the
-B8BITMIME
command line flag,
and undeclared 8-bit data, that is,
input that just happens to be eight bits.
There are three basic operations that can happen:
undeclared 8-bit data can be automatically converted to 8BITMIME,
undeclared 8-bit data can be passed as-is without conversion to MIME
(``just send 8''),
and declared 8-bit data can be converted to 7-bits
for transmission to a non-8BITMIME mailer.
The possible
actions
are:

In all cases properly declared 8BITMIME data will be converted to 7BIT
as needed.

ErrorHeader=file-or-message

[E]
Prepend error messages with the indicated message.
If it begins with a slash,
it is assumed to be the pathname of a file
containing a message (this is the recommended setting).
Otherwise, it is a literal message.
The error file might contain the name, email address, and/or phone number
of a local postmaster who could provide assistance
to end users.
If the option is missing or null,
or if it names a file which does not exist or which is not readable,
no message is printed.

ErrorMode=x

[e] Dispose of errors using mode
x. The values for x are:

p

Print error messages (default)

q

No messages, just give exit status

m

Mail back errors

w

Write back errors (mail if user not logged in)

e

Mail back errors and give zero exit stat always

FallbackMXhost=fallbackhost

[V] If specified, the fallbackhost
acts like a very low priority MX on every host.
This is intended to be used by sites with poor network connectivity.
Messages which are undeliverable due to temporary address failures
(for example, DNS failure)
also go to the FallBackMX host.

ForkEachJob

[Y] If set,
deliver each job that is run from the queue in a separate process.
Use this option if you are short of memory,
since the default tends to consume considerable amounts of memory
while the queue is being processed.

ForwardPath=path

[J] Set the path for searching for users' .forward files.
The default is ``$z/.forward''.
Some sites that use the automounter may prefer to change this to
``/var/forward/$u''
to search a file with the same name as the user in a system directory.
It can also be set to a sequence of paths separated by colons;
sendmail
stops at the first file it can successfully and safely open.
For example,
``/var/forward/$u:$z/.forward''
will search first in /var/forward/username
and then in
~username.forward
(but only if the first file does not exist).

HelpFile=file

[H]
Specify the help file
for SMTP.
If no file name is specified, "helpfile" is used.

HoldExpensive

[c]
If an outgoing mailer is marked as being expensive,
don't connect immediately.
This requires that queueing be compiled in,
since it will depend on a queue run process to
actually send the mail.

HostsFile=path

[no short name]
The path to the hosts database,
normally
``/etc/hosts .''
This option is only consulted when sendmail
is canonifying addresses,
and then only when
``files''
is in the
``hosts''
service switch entry.
In particular, this file is
never
used when looking up host addresses;
that is under the control of the system
gethostbyname(SLIB)
routine.

HostStatusDirectory=path

[no short name]
The location of the long term host status information.
When set,
information about the status of hosts
(for example, host down or not accepting connections)
will be shared between all
sendmail
processes;
normally, this information is only held within a single queue run.
This option requires a connection cache of at least 1 to function.
If the option begins with a leading `/',
it is an absolute pathname;
otherwise,
it is relative to the mail queue directory.
A suggested value for sites desiring persistent host status is
``.hoststat''
(that is, a subdirectory of the queue directory).

[no short name]
Sets a default map specification for LDAP maps.
The value should only contain LDAP specific settings
such as
``"-h host -p port -d bindDN" .''
The settings will be used for all LDAP maps
unless the individual map specification overrides a setting.
This option should be set before any LDAP maps are defined.

LogLevel=n

[L]
Set the log level to
n .
Defaults to 9.

Mxvalue

[no long version]
Set the macro
x
to
value .
This is intended only for use from the command line.
The
-M
flag is preferred.

MatchGECOS

[G]
Allow fuzzy matching on the GECOS field.
If this flag is set,
and the usual user name lookups fail
(that is, there is no alias with this name and a
getpwnam
fails),
sequentially search the password file
for a matching entry in the GECOS field.
This also requires that MATCHGECOS
be turned on during compilation.
This option is not recommended.

MaxAliasRecursion=N

[no short name]
The maximum depth of alias recursion (default: 10).

MaxDaemonChildren=N

[no short name]
If set,
sendmail
will refuse connections when it has more than
N
children processing incoming mail or automatic queue runs.
This does not limit the number of outgoing connections.
If not set, there is no limit to the number of children --
that is, the system load averaging controls this.

MaxHeadersLength=N

[no short name]
The maximum length of the sum of all headers.
This can be used to prevent a denial of service attack.
The default is no limit.

MaxHopCount=N

[h]
The maximum hop count.
Messages that have been processed more than
N
times are assumed to be in a loop and are rejected.
Defaults to 25.

MaxMessageSize=N

[no short name]
Specify the maximum message size
to be advertised in the ESMTP EHLO response.
Messages larger than this will be rejected.

MaxMimeHeaderLength=N[/M]

[no short name]
Sets the maximum length of certain MIME header field values
to
N
characters.
For some of these headers which take parameters,
the maximum length of each parameter is set to
M
if specified. If
/M
is not specified, one half of
N
will be used.
By default,
these values are 0, meaning no checks are done.

MaxQueueRunSize=N

[no short name]
The maximum number of jobs that will be processed
in a single queue run.
If not set, there is no limit on the size.
If you have very large queues or a very short queue run interval
this could be unstable.
However, since the first
N
jobs in queue directory order are run (rather than the
N
highest priority jobs)
this should be set as high as possible to avoid
``losing''
jobs that happen to fall late in the queue directory.

MaxRecipientsPerMessage=N

[no short name]
The maximum number of recipients that will be accepted per message
in an SMTP transaction.
Note: setting this too low can interfere with sending mail from
MUAs that use SMTP for initial submission.
If not set, there is no limit on the number of recipients per envelope.

MeToo

[m]
Send to me too,
even if I am in an alias expansion.
This option is deprecated
and will be removed from a future version.

MinFreeBlocks=N

[b]
Insist on at least
N
blocks free on the filesystem that holds the queue files
before accepting email via SMTP.
If there is insufficient space
sendmail
gives a 452 response
to the MAIL command.
This invites the sender to try again later.

MinQueueAge=age

[no short name]
Don't process any queued jobs
that have been in the queue less than the indicated time interval.
This is intended to allow you to get responsiveness
by processing the queue fairly frequently
without thrashing your system by trying jobs too often.
The default units are minutes.

MustQuoteChars=s

[no short name]
Sets the list of characters that must be quoted if used in a full name
that is in the phrase part of a ``phrase <address>'' syntax.
The default is ``´.''.
The characters ``@,;:\()[]'' are always added to this list.

NoRecipientAction

[no short name]
The action to take when you receive a message that has no valid
recipient headers (To:, Cc:, Bcc:, or Apparently-To: --
the last included for back compatibility with old
sendmail.
It can be
None
to pass the message on unmodified,
which violates the protocol,
Add-To
to add a To: header with any recipients it can find in the envelope
(which might expose Bcc: recipients),
Add-Apparently-To
to add an Apparently-To: header
(this is only for back-compatibility
and is officially deprecated),
Add-To-Undisclosed
to add a header
``"To: undisclosed-recipients:;"''
to make the header legal without disclosing anything,
or
Add-Bcc
to add an empty Bcc: header.

OldStyleHeaders

[o]
Assume that the headers may be in old format,
that is,
spaces delimit names.
This actually turns on
an adaptive algorithm:
if any recipient address contains a comma, parenthesis,
or angle bracket,
it will be assumed that commas already exist.
If this flag is not on,
only commas delimit names.
Headers are always output with commas between the names.
Defaults to off.

OperatorChars=charlist

[$o macro]
The list of characters that are considered to be
``operators ,''
that is, characters that delimit tokens.
All operator characters are tokens by themselves;
sequences of non-operator characters are also tokens.
White space characters separate tokens
but are not tokens themselves -- for example,
``AAA.BBB''
has three tokens, but
``"AAA BBB"''
has two.
If not set, OperatorChars defaults to
``.:@[] ;''
additionally, the characters
``()<>,;''
are always operators.
Note that OperatorChars must be set in the
configuration file before any rulesets.

PidFile=filename

[no short name]
Filename of the pid file.
(default is _PATH_SENDMAILPID).
The
filename
is macro-expanded before it is opened.

PostmasterCopy=postmaster

[P]
If set,
copies of error messages will be sent to the named
postmaster .
Only the header of the failed message is sent.
Errors resulting from messages with a negative precedence will not be sent.
Since most errors are user problems,
this is probably not a good idea on large sites,
and arguably contains all sorts of privacy violations,
but it seems to be popular with certain operating systems vendors.
The address is macro expanded
at the time of delivery.
Defaults to no postmaster copies.

PrivacyOptions=opt,opt,...

[p]
Set the privacy
options.
``Privacy'' is really a misnomer;
many of these are just a way of insisting on stricter adherence
to the SMTP protocol.
The
opt ions
can be selected from:

public

Allow open access

needmailhelo

Insist on HELO or EHLO command before MAIL

needexpnhelo

Insist on HELO or EHLO command before EXPN

noexpn

Disallow EXPN entirely, implies noverb.

needvrfyhelo

Insist on HELO or EHLO command before VRFY

novrfy

Disallow VRFY entirely

noetrn

Disallow ETRN entirely

noverb

Disallow VERB entirely

restrictmailq

Restrict mailq command

restrictqrun

Restrict -q command line flag

noreceipts

Don't return success DSNs

nobodyreturn

Don't return the body of a message with DSNs

goaway

Disallow essentially all SMTP status queries

authwarnings

Put X-Authentication-Warning: headers in messages

The ``goaway'' pseudo-flag sets all flags except
``noreceipts,'' ``restrictmailq,'' ``restrictqrun,'' ``noetrn,'' and
``nobodyreturn .'' If mailq is restricted,
only people in the same group as the queue directory
can print the queue.
If queue runs are restricted,
only root and the owner of the queue directory
can run the queue.
Authentication Warnings add warnings about various conditions
that may indicate attempts to spoof the mail system,
such as using an non-standard queue directory.

ProcessTitlePrefix=string

[no short name]
Prefix the process title shown on 'ps' listings with
string .
The
string
will be macro processed.

QueueDirectory=dir

[Q]
Use the named
dir
as the queue directory.
To use multiple queues, supply a value ending with an asterisk.
For example,
/var/spool/mqueue/q*
will use all of the directories or symbolic links to directories
beginning with
q
in
/var/spool/mqueue
as queue directories.
Do not change the queue directory structure
while sendmail is running.

QueueFactor=factor

[q]
Use
factor
as the multiplier in the map function
to decide when to just queue up jobs rather than run them.
This value is divided by the difference between the current load average
and the load average limit
(QueueLA option)
to determine the maximum message priority
that will be sent.
Defaults to 600000.

QueueLA=LA

[x]
When the system load average exceeds
LA ,
just queue messages
(that is, don't try to send them).
Defaults to 8 multiplied by
the number of processors online on the system
(if that can be determined).

QueueSortOrder=algorithm

[no short name]
Sets the
algorithm
used for sorting the queue.
Only the first character of the value is used.
Legal values are
``host''
(to order by the name of the first host name of the first recipient),
``filename''
(to order by the name of the queue file name),
``time''
(to order by the submission time),
and
``priority''
(to order by message priority).
Host ordering makes better use of the connection cache,
but may tend to process low priority messages
that go to a single host
over high priority messages that go to several hosts;
it probably shouldn't be used on slow network links.
Filename ordering saves the overhead of
reading all of the queued items
before starting the queue run.
Time ordering is almost always a bad idea,
since it allows large, bulk mail to go out
before smaller, personal mail,
but may have applicability on some hosts with very fast connections.
Priority ordering is the default.

QueueTimeout=timeout

[T]
A synonym for
``Timeout.queuereturn .''
Use that form instead of the
``QueueTimeout''
form.

RandFile

[no short name]
Name of file containing random data or the name of the Unix socket
if EGD is used.
A (required) prefix "egd:" or "file:" specifies the type.
STARTTLS requires this filename if the compile flag HASURANDOM is not set
(see sendmail/README).

ResolverOptions=options

[I]
Set resolver options.
Values can be set using
+ flag
and cleared using
- flag;
the flag s
can be
``debug ,''
``aaonly ,''
``usevc ,''
``primary ,''
``igntc ,''
``recurse ,''
``defnames ,''
``stayopen ,''
or
``dnsrch .''
The string
``HasWildcardMX''
(without a
+
or
- )
can be specified to turn off matching against MX records
when doing name canonifications.
N.B.
Prior to 8.7,
this option indicated that the name server be responding
in order to accept addresses.
This has been replaced by checking to see
if the
``dns''
method is listed in the service switch entry for the
``hosts''
service.

RrtImpliesDsn

[R]
If this option is set, a
``Return-Receipt-To:''
header causes the request of a DSN, which is sent to
the envelope sender as required by RFC1891,
not to the address given in the header.

RunAsUser=user

[no short name]
The
user
parameter may be a user name
(looked up in
/etc/passwd )
or a numeric user id;
either form can have
``":group"''
attached
(where group can be numeric or symbolic).
If set to a non-zero (non-root) value,
sendmail
will change to this user id shortly after startup.
(When running as a daemon,
it changes to this user after accepting a connection
but before reading any
SMTP commands.)
This avoids a certain class of security problems.
However, this means that all
``.forward''
and
``:include:''
files must be readable by the indicated
user
and all files to be written must be writable by
user
Also, all file and program deliveries will be marked unsafe
unless the option
DontBlameSendmail=NonRootAddrSafe
is set,
in which case the delivery will be done as
user .
It is also incompatible with the
SafeFileEnvironment option.
In other words, it may not actually add much to security on an average system,
and may in fact detract from security
(because other file permissions must be loosened).
However, it should be useful on firewalls and other
places where users don't have accounts and the aliases file is
well constrained.

RecipientFactor=fact

[y]
The indicated
factor
is added to the priority (thus
lowering
the priority of the job)
for each recipient,
that is, this value penalizes jobs with large numbers of recipients.
Defaults to 30000.

RefuseLA=LA

[X]
When the system load average exceeds
LA ,
refuse incoming SMTP connections.
Defaults to 12 multiplied by
the number of processors online on the system
(if that can be determined).

RetryFactor=fact

[Z]
The
factor
is added to the priority
every time a job is processed.
Thus,
each time a job is processed,
its priority will be decreased by the indicated value.
In most environments this should be positive,
since hosts that are down are all too often down for a long time.
Defaults to 90000.

SafeFileEnvironment=dir

[no short name]
If this option is set,
sendmail
will do a chroot
call into the indicated
directory
before doing any file writes.
If the file name specified by the user begins with
dir ,
that partial path name will be stripped off before writing,
so (for example)
if the SafeFileEnvironment variable is set to
``/safe''
then aliases of
``/safe/logs/file''
and
``/logs/file''
actually indicate the same file.
Additionally, if this option is set,
sendmail
refuses to deliver to symbolic links.

SaveFromLine

[f]
Save
Unix-style
``From''
lines at the front of headers.
Normally they are assumed redundant
and discarded.

SendMimeErrors

[j]
If set, send error messages in MIME format
(see RFC2045 and RFC1344 for details).
If disabled,
sendmail
will not return the DSN keyword in response to an EHLO
and will not do Delivery Status Notification processing as described in
RFC1891.

ServerCertFile

[no short name]
File containing the certificate of the server, that is, this certificate
is used when sendmail acts as server.

ServerKeyFile

[no short name]
File containing the private key belonging to the server certificate.

ServiceSwitchFile=filename

[no short name]
If your host operating system has a service switch abstraction,
that service will be consulted and this option is ignored.
Otherwise, this is the name of a file
that provides the list of methods used to implement particular services.
The syntax is a series of lines,
each of which is a sequence of words.
The first word is the service name,
and following words are service types.
The services that
sendmail
consults directly are
``aliases''
and
``hosts.''
Service types can be
``dns ,''
``nis ,''
``nisplus ,''
or
``files''
(with the caveat that the appropriate support
must be compiled in
before the service can be referenced).
If ServiceSwitchFile is not specified, it defaults to
/etc/mail/service.switch.
If that file does not exist, the default switch is:

aliases files
hosts dns nis files

SevenBitInput

[7]
Strip input to seven bits for compatibility with old systems.
This shouldn't be necessary.

SingleLineFromHeader

[no short name]
If set, From: lines that have embedded newlines are unwrapped
onto one line.
This is to get around a botch in Lotus Notes
that apparently cannot understand legally wrapped RFC822 headers.

SingleThreadDelivery

[no short name]
If set, a client machine will never try to open two SMTP connections
to a single server machine at the same time,
even in different processes.
That is, if another
sendmail
is already talking to some host a new
sendmail
will not open another connection.
This property is of mixed value;
although this reduces the load on the other machine,
it can cause mail to be delayed
(for example, if one
sendmail
is delivering a huge message, other
sendmails
won't be able to send even small messages).
Also, it requires another file descriptor
(for the lock file)
per connection, so you may have to reduce the
ConnectionCacheSize
option to avoid running out of per-process file descriptors.
Requires the
HostStatusDirectory
option.

[S]
Log summary statistics in the named
file.
If no file name is specified, "statistics" is used.
If not set,
no summary statistics are saved.
This file does not grow in size.
It can be printed using the
mailstats (8)
program.

SuperSafe

[s]
Be super-safe when running things,
that is,
always instantiate the queue file,
even if you are going to attempt immediate delivery.
sendmail
always instantiates the queue file
before returning control to the client
under any circumstances.
This should really
always
be set.

TempFileMode=mode

[F]
The file mode for queue files.
It is interpreted in octal by default.
Defaults to 0600.

[t]
Set the local time zone info to
tzinfo - for example,
``PST8PDT.''
Actually, if this is not set,
the TZ environment variable is cleared (so the system default is used);
if set but null, the user's TZ variable is used,
and if set and non-null the TZ variable is set to this value.

TrustedUser=user

[no short name]
The
user
parameter may be a user name
(looked up in
/etc/passwd )
or a numeric user id.
Trusted user for file ownership and starting the daemon. If set, generated
alias databases and the control socket (if configured) will automatically
be owned by this user.

TryNullMXList

[w]
If this system is the
``best''
(that is, lowest preference)
MX for a given host,
its configuration rules should normally detect this situation
and treat that condition specially
by forwarding the mail to a UUCP feed,
treating it as local,
or whatever.
However, in some cases (such as Internet firewalls)
you may want to try to connect directly to that host
as though it had no MX records at all.
Setting this option causes
sendmail
to try this.
The downside is that errors in your configuration
are likely to be diagnosed as
``host unknown''
or
``message timed out''
instead of something more meaningful.
This option is disrecommended.

UnixFromLine=fromline

[$l macro]
Defines the format used when
sendmail
must add a UNIX-style From_ line
(that is, a line beginning
``From<space>user ).''
Defaults to
``"From $g $d".''
Don't change this unless your system uses a different UNIX mailbox format
(very unlikely).

UnsafeGroupWrites

[no short name]
If set,
:include: and .forward files that are group writable are considered
``unsafe'';
that is,
they cannot reference programs or write directly to files.
World writable :include: and .forward files
are always unsafe.

UseErrorsTo

[l]
If there is an
``Errors-To:''
header, send error messages to the addresses listed there.
They normally go to the envelope sender.
Use of this option causes
sendmail
to violate RFC 1123.
This option is disrecommended and deprecated.

UserDatabaseSpec=udbspec

[U]
The user database specification.

Verbose

[v]
Run in verbose mode.
If this is set,
sendmail
adjusts options
HoldExpensive
(old
c )
and
DeliveryMode
(old
d )
so that all mail is delivered completely
in a single job
so that you can see the entire delivery process.
Option
Verbose
should
never
be set in the configuration file;
it is intended for command line use only.

XscriptFileBufferSize=threshold

[no short name]
Set the
threshold ,
in bytes,
before a memory-based
queue transcript file
becomes disk-based.
The default is 4096 bytes.

All options can be specified on the command line using the
-O or -o flag,
but most will cause
sendmail
to relinquish its setuid permissions.
The options that will not cause this are
SevenBitInput [7],
EightBitMode [8],
MinFreeBlocks [b],
CheckpointInterval [C],
DeliveryMode [d],
ErrorMode [e],
IgnoreDots [i],
SendMimeErrors [j],
LogLevel [L],
MeToo [m],
OldStyleHeaders [o],
PrivacyOptions [p],
SuperSafe [s],
Verbose [v],
QueueSortOrder,
MinQueueAge,
DefaultCharSet,
DialDelay,
NoRecipientAction,
ColonOkInAddr,
MaxQueueRunSize,
SingleLineFromHeader,
and
AllowBogusHELO.
Actually, PrivacyOptions (p) given on the
command line are added to those already specified in the
sendmail.cf
file, that is, they cannot be reset.
Also, M (define macro) when defining the r or s macros
is also considered
``safe.''

P--precedence definitions

Values for the ``Precedence:'' field may be defined using the
P
control line.
The syntax of this field is:

Pname=num

When the
name
is found in a ``Precedence:'' field, the message class is set to
num.
Higher numbers mean higher precedence.
Numbers below zero have the special property
that if an error occurs during processing, the body of the message will
not be returned; this is expected to be used for ``bulk'' mail
such as through mailing lists.
The default precedence is zero.
An example
list of precedences is:

Pfirst-class=0
Pspecial-delivery=100
Plist=-30
Pbulk=-60
Pjunk=-100

People writing mailing list exploders
are encouraged to use
``Precedence: list''.
Older versions of
sendmail
(which discarded all error returns for negative precedences)
did not recognize this name, giving it a default precedence of zero.
This allows list maintainers to see error returns
on both old and new versions of
sendmail.

V--configuration version level

To provide compatibility with old configuration files,
the V
line has been added to define some very basic semantics
of the configuration file.
These are not intended to be long term supports;
rather, they describe compatibility features
which will probably be removed in future releases.

NOTE:
These version
``levels''
have nothing
to do with the version
``number''
on the files.
For example,
as of this writing
version 8 configuration files
(specifically, 8.6)
used version level 5 configurations.

``Old'' configuration files are defined as version level one.

Version level two files make the following changes:

Host name canonification ($[ ... $])
appends a dot if the name is recognized;
this gives the configuration file a way of finding out if anything matched.
(Actually, this just initializes the
``host''
map with the
-a
flag--you can reset it to anything you prefer
by declaring the map explicitly.)
Default host name extension is consistent throughout processing;
version level one configurations turned off domain extension
(that is, adding the local domain name)
during certain points in processing.
Version level two configurations are expected to include a trailing dot
to indicate that the name is already canonical.

Local names that are not aliases
are passed through a new distinguished ruleset five;
this can be used to append a local relay.
This behavior can be prevented by resolving the local name
with an initial ``@''.
That is, something that resolves to a local mailer and a user name of
vikki
will be passed through ruleset five,
but a user name of
@vikki
will have the ``@'' stripped,
will not be passed through ruleset five,
but will otherwise be treated the same as the prior example.
The expectation is that this might be used to implement a policy
where mail sent to
vikki
was handled by a central hub,
but mail sent to
vikki@localhost
was delivered directly.

Version level three files
allow # initiated comments on all lines.
Exceptions are backslash escaped # marks
and the $# syntax.

Version level four configurations
are completely equivalent to level three
for historical reasons.

Version level five configuration files
change the default definition of
$w
to be just the first component of the hostname.

Version level six configuration files
change many of the local processing options
(such as aliasing and matching the beginning of the address for
`|' characters) to be mailer flags;
this allows fine-grained control over the special local processing.
Level six configuration files may also use long option names.
The ColonOkInAddr
option (to allow colons in the local-part of addresses)
defaults on
for lower numbered configuration files;
the configuration file requires some additional intelligence
to properly handle the RFC 822 group construct.

Version level seven configuration files
used new option names to replace old macros
($e became SmtpGreetingMessage ,
$l became UnixFromLine ,
and $o became OperatorChars).
Also, prior to version seven, the F=q
flag (use 250 instead of 252 return value for
SMTP VRFY commands) was assumed.

Version level eight configuration files allow
$# on the left hand side of ruleset lines.

Version level nine configuration files allow
parentheses in rulesets, that is, they are not treated
as comments and hence removed.

The V line may have an optional /vendor
to indicate that this configuration file uses modifications
specific to a particular vendor. You can use
``/Berkeley'' to emphasize that this configuration file
uses the Berkeley dialect of sendmail.

K--key file declaration

Special maps can be defined using the line:

Kmapname mapclass arguments

The
mapname
is the handle by which this map is referenced in the rewriting rules.
The
mapclass
is the name of a type of map;
these are compiled in to
sendmail .
The
arguments
are interpreted depending on the class;
typically,
there would be a single argument naming the file containing the map.

Maps are referenced using the syntax:

$( mapkey $@ arguments $: default $)

where either or both of the arguments or default
portion may be omitted. The "$@ arguments"
may appear more than once. The indicated key and
arguments
are passed to the appropriate mapping function.
If it returns a value, it replaces the input.
If it does not return a value and the
default
is specified, the
default
replaces the input.
Otherwise, the input is unchanged.

The arguments
are passed to the map for arbitrary use.
Most map classes can interpolate these arguments
into their values using the syntax
``%n'' (where n
is a digit)
to indicate the corresponding
argument .
Argument
``%0''
indicates the database key.
For example, the rule

R$- ! $+ $: $(uucp $1 $@ $2 $: %1 @ %0 . UUCP $)

Looks up the UUCP name in a (user defined) UUCP map;
if not found it turns it into
``.UUCP''
form.
The database might contain records like:

decvax %1@%0.DEC.COM
research %1@%0.ATT.COM

Note that
default
clauses never do this mapping.

The built in map with both name and class
``host''
is the host name canonicalization lookup.
Thus,
the syntax:

$(host hostname$)

is equivalent to:

$[hostname$]

There are many defined classes.

dbm

Database lookups using the

ndbmNS

library.
sendmail
must be compiled with
NDBM
defined.

btree

Database lookups using the btree interface to the Berkeley DB
library.
sendmail
must be compiled with
NEWDB
defined.

hash

Database lookups using the hash interface to the Berkeley DB
library.
sendmail
must be compiled with
NEWDB
defined.

nis

NIS lookups.
sendmail
must be compiled with
NIS
defined.

nisplus

NIS+ lookups.
sendmail
must be compiled with
NISPLUS
defined.
The argument is the name of the table to use for lookups,
and the
-k
and
-v
flags may be used to set the key and value columns respectively.

hesiod

Hesiod lookups.
sendmail
must be compiled with
HESIOD
defined.

ldap

LDAP X500 directory lookups.
sendmail
must be compiled with
LDAPMAP
defined.
The map supports most of the standard arguments
and most of the command line arguments of the
ldapsearch
program.
Note that,
by default,
if a single query matches multiple values,
only the first value will be returned
unless the
-z
(value separator)
map flag is set.
Also, the
-1
map flag will treat a multiple value return
as if there were no matches.

netinfo

NeXT NetInfo lookups.
sendmail
must be compiled with
NETINFO
defined.

text

Text file lookups.
The format of the text file is defined by the
-k
(key field number),
-v
(value field number),
and
-z
(field delimiter)
flags.

ph

PH query map.
Contributed and supported by
Mark Roth, roth@uiuc.edu.
For more information,
consult the web site
``http://www-wsg.cso.uiuc.edu/sendmail/sendmail-phmap/ .''

nsd

nsd map for IRIX 6.5 and later.
Contributed and supported by Bob Mende of SGI,
mende@sgi.com.

stab

Internal symbol table lookups.
Used internally for aliasing.

implicit

Really should be called
``alias''
-- this is used to get the default lookups
for alias files,
and is the default if no class is specified for alias files.

user

Looks up users using
getpwnam(S).
The
-v
flag can be used to specify the name of the field to return
(although this is normally used only to check the existence
of a user).

host

Canonifies host domain names.
Given a host name it calls the name server
to find the canonical name for that host.

bestmx

Returns the best MX record for a host name given as the key.
The current machine is always preferred -
that is, if the current machine is one of the hosts listed as a
lowest-preference MX record, then it will be guaranteed to be returned.
This can be used to find out if this machine is the target for an MX record,
and mail can be accepted on that basis.
If the
-z
flag is given, then all MX names are returned,
separated by the given delimiter.

sequence

The arguments on the `K' line are a list of maps;
the resulting map searches the argument maps in order
until it finds a match for the indicated key.
For example, if the key definition is:

Kmap1 ...
Kmap2 ...
Kseqmap sequence map1 map2

then a lookup against
``seqmap''
first does a lookup in map1.
If that is found, it returns immediately.
Otherwise, the same key is used for map2.

syslog

the key is logged via
syslogd (8).
The lookup returns the empty string.

switch

Much like the
``sequence''
map except that the order of maps is determined by the service switch.
The argument is the name of the service to be looked up;
the values from the service switch are appended to the map name
to create new map names.
For example, consider the key definition:

Kali switch aliases

together with the service switch entry:

aliases nis files

This causes a query against the map
``ali''
to search maps named
``ali.nis''
and
``ali.files''
in that order.

dequote

Strip double quotes (") from a name.
It does not strip backslashes,
and will not strip quotes if the resulting string
would contain unscannable syntax
(that is, basic errors like unbalanced angle brackets;
more sophisticated errors such as unknown hosts are not checked).
The intent is for use when trying to accept mail from systems such as
DECnet
that routinely quote odd syntax such as

"49ers::ubell"

A typical usage is probably something like:

Kdequote dequote

...

R$- $: $(dequote $1 $)
R$- $+ $: $>3 $1 $2

Care must be taken to prevent unexpected results;
for example,

"|someprogram < input > output"

will have quotes stripped,
but the result is probably not what you had in mind.
Fortunately these cases are rare.

regex

The map definition on the
K
line contains a regular expression.
Any key input is compared to that expression using the
POSIX regular expressions routines regcomp(), regerr(), and regexec().
Refer to the documentation for those routines for more information
about the regular expression matching.
No rewriting of the key is done if the
-m
flag is used. Without it, the key is discarded or if
-s
if used, it is substituted by the substring matches, delimited by
$|
or the string specified with the the
-d
flag. The flags available for the map are

The
-s
flag can include an optional parameter which can be used
to select the substrings in the result of the lookup. For example,

-s1,3,4

Note: to match a
$ in a string, $$
must be used.
If the pattern contains spaces, they must be replaced
with the blank substitution character, unless it is
space itself.

program

The arguments on the
K
line are the pathname to a program and any initial parameters to be passed.
When the map is called,
the key is added to the initial parameters
and the program is invoked
as the default user/group id.
The first line of standard output is returned as the value of the lookup.
This has many potential security problems,
and has terrible performance;
it should be used only when absolutely necessary.

macro

Set or clear a macro value.
To set a macro,
pass the value as the first argument in the map lookup.
To clear a macro,
do not pass an argument in the map lookup.
The map always returns the empty string.
Example of typical usage include:

Perform simple arithmetic operations.
The operation is given as key, currently +, -, *, /,
l (for less than), and = are supported.
The two operands are given as arguments.
The lookup returns the result of the computation,
that is TRUE or FALSE
for comparisons, integer values otherwise.
All options which are possible for maps are ignored.
A simple example is:

Most of these accept as arguments the same optional flags
and a filename
(or a mapname for NIS;
the filename is the root of the database path,
so that
``.db''
or some other extension appropriate for the database type
will be added to get the actual database name).

Known flags are:

-o

Indicates that this map is optional - that is,
if it cannot be opened,
no error is produced,
and
sendmail
will behave as if the map existed but was empty.

-N, -O

If neither
-N
or
-O
are specified,
sendmail
uses an adaptive algorithm to decide whether or not to look for null bytes
on the end of keys.
It starts by trying both;
if it finds any key with a null byte it never tries again without a null byte
and vice versa.
If
-N
is specified it never tries without a null byte and
if
-O
is specified it never tries with a null byte.
Setting one of
these can speed matches but are never necessary.
If both
-N
and
-O
are specified,
sendmail
will never try any matches at all --
that is, everything will appear to fail.

-ax

Append the string
x
on successful matches.
For example, the default
host
map appends a dot on successful matches.

-Tx

Append the string
x
on temporary failures.
For example,
x
would be appended if a DNS lookup returned
``server failed''
or an NIS lookup could not locate a server.
See also the
-t
flag.

-f

Do not fold upper to lower case before looking up the key.

-m

Match only (without replacing the value).
If you only care about the existence of a key and not the value
(as you might when searching the NIS map
``hosts.byname''
for example),
this flag prevents the map from substituting the value.
However, the -a argument is still appended on a match,
and the default is still taken if the match fails.

-kkeycol

The key column name (for NIS+) or number
(for text lookups).
For LDAP maps this is an LDAP filter string
in which %s is replaced with the literal contents of the lookup key
and %0 is replaced with the LDAP escaped contents of the lookup key
according to RFC2254.

-vvalcol

The value column name (for NIS+) or number
(for text lookups).
For LDAP maps this is the name of one or more
attributes to be returned;
multiple attributes can be separated by commas.
If not specified, all attributes found in the match
will be returned.

-zdelim

The column delimiter (for text lookups).
It can be a single character or one of the special strings
``\n''
or
``\t''
to indicate newline or tab respectively.
If omitted entirely,
the column separator is any sequence of white space.
For LDAP maps this is the separator character
to combine multiple values
into a single return string.
If not set,
the LDAP lookup will only return the first match found.

-t

Normally, when a map attempts to do a lookup
and the server fails
(e.g.,
sendmail
couldn't contact any name server;
this is
not
the same as an entry not being found in the map),
the message being processed is queued for future processing.
The
-t
flag turns off this behavior,
letting the temporary failure (server down)
act as though it were a permanent failure (entry not found).
It is particularly useful for DNS lookups,
where someone else's misconfigured name server can cause problems
on your machine.
However, care must be taken to ensure that you don't bounce mail
that would be resolved correctly if you tried again.
A common strategy is to forward such mail
to another, possibly better connected, mail server.

-D

Perform no lookup in deferred delivery mode.
This flag is set by default for the
host
map.

-Sspacesub

The character to use to replace space characters
after a successful map lookup (esp. useful for regex
and syslog maps).

-sspacesub

For the dequote map only,
the character to use to replace space characters
after a successful dequote.

-q

Don't dequote the key before lookup.

-Llevel

For the syslog map only, it specifies the level
to use for the syslog call.

-A

When rebuilding an alias file,
the -A
flag causes duplicate entries in the text version
to be merged. For example, two entries:

list: user1, user2
list: user3

would be treated as though it were the single entry

list: user1, user2, user3

in the presence of the
-A
flag.

The following additional flags are present in the ldap map only:

-R

Do not auto chase referrals. sendmail must be compiled with
-DLDAP_REFERRALS
to use this flag.

-n

Retrieve attribute names only.

-rderef

Set the alias dereference option to one of never, always, search, or find.

-sscope

Set search scope to one of base, one (one level), or sub (subtree).

-hhost

LDAP server hostname.

-bbase

LDAP search base.

-pport

LDAP service port.

-ltimelimit

Time limit for LDAP queries.

-Zsizelimit

Size (number of matches) limit for LDAP queries.

-ddistinguished_name

The distinguished name to use to login to the LDAP server.

-Mmethod

The method to authenticate to the LDAP server.
Should be one of
LDAP_AUTH_NONE,
LDAP_AUTH_SIMPLE,
or
LDAP_AUTH_KRBV4.

-Ppasswordfile

The file containing the secret key for the
LDAP_AUTH_SIMPLE
authentication method
or the name of the Kerberos ticket file for
LDAP_AUTH_KRBV4.,

-1

Force LDAP searches to only succeed if a single match is found.
If multiple values are found,
the search is treated as if no match was found.

The
dbm
map appends the strings
``.pag''
and
``.dir''
to the given filename;
the
hash
and
btree
maps append
``.db .''
For example, the map specification

Kuucp dbm -o -N /etc/mail/uucpmap

specifies an optional map named
``uucp''
of class
``dbm ;''
it always has null bytes at the end of every string,
and the data is located in
/etc/mail/uucpmap.{dir,pag}.

The program
makemap(ADMN)
can be used to build any of the three database-oriented maps.
It takes the following flags:

-f

Do not fold upper to lower case in the map.

-N

Include null bytes in keys.

-o

Append to an existing (old) file.

-r

Allow replacement of existing keys;
normally, re-inserting an existing key is an error.

-v

Print what is happening.

The sendmail
daemon does not have to be restarted to read the new maps
as long as you change them in place;
file locking is used so that the maps won't be read
while they are being updated.